The present invention relates generally to the field of locking devices for windows, and more particularly, is directed to a recessed type of lock suitable for use with double hung windows.
The double hung type of window installation has been commonly employed for many years both for use in and about residential constructions and also for commercial and industrial buildings. The double hung window constructions have usually been provided with some type of a lock which interacts between the upper rail of the lower sash and the lower rail of the upper sash to secure the upper and lower sash together in a manner to discourage entry into the interior of the building through the window opening. For this purpose, many types of locks have been utilized, for example, the common cam type sash lock, wedge type ventilating lock, key operated cam latches, key operated pin type locks, friction type securing devices and other more or less complicated structures. All of these devices are commonly secured to the sash by the use of wood screws of sheet metal screws and all suffer from the common problems that the screws can be rather easily worked out of the sash by a determined intruder who need utilize only rather basic easily available, prying type of tools.
In an effort to improve over the screw connected locking devices, other workers in the art have employed nails or other elongate members which insert through pre-drilled openings provided in overlapping portions of the sash members. These nail type locking devices all suffer from a common problem in that portions of the elongate locking members project interiorly from the lower sash. Accordingly they are easily removed from within the building by simply grasping and pulling the member from its associated opening. Under these circumstances all a would-be thief need do to defeat the purpose of a nail type locking device is to break the glass, reach interiorly, and then simply pull the elongate member from its associated opening, thereby freeing the lower sash for easy opening.